Method of making a knife with an oblique bolster

ABSTRACT

The invention relates to a method for producing a knife ( 1 ) with a blade ( 2 ), a bolster ( 3 ) and a handle, in particular a tang ( 4 ), forged from a single piece of flat steel material ( 5 ), wherein, before forging, the flat material ( 5 ) is upset in the region between the blade ( 2 ) and the handle or tang ( 4 ) to form a bead ( 6 ), the longitudinal axis (LW) of which is arranged transversely in relation to the longitudinal axis (LM) of the knife, and is then formed by forging to form a bolster ( 3 ), which has at least one side edge (K 2 ) positioned obliquely in relation to the longitudinal axis (LM) of the knife, wherein the longitudinal axis (LW) of the bead ( 6 ), which later forms the bolster, is oriented obliquely in relation to the longitudinal axis (LM) of the knife ( 1 ).

The invention relates to a method of making a knife with a blade, a bolster, and a handle, in particular with a tang, forged from a single piece of flat steel, wherein before forging the flat piece is upset to form in the region between the blade and the handle or tang a bead whose longitudinal axis extends transversely to the knife longitudinal axis and thereafter is forged to form a bolster that has at least one side edge extending obliquely to the knife longitudinal axis.

To produce a knife with a bolster it is known to forge the knife from a single flat piece that has been upset to form a bead in the region that during subsequent forging is shaped to form the bolster. If the bolster is to extend obliquely to the longitudinal axis or to the longitudinal extension of the knife, substantial deformation is required during forging, since significant amounts of material must be driven toward the blade of the knife. The forging can thus lead an insufficient mold filling and thus to an unstable process so that significant rejects are produced.

The object of the invention is to improve a method of the type described above such that the volume of the bead is so well predistributed that during forging an optimal material distribution and mold filling is achieved.

This object is attained according to the invention in that the longitudinal axis of the bead later forming the bolster is aligned obliquely to the longitudinal axis of the knife.

It is possible with the method according to the invention to optimally provide the material for the bolster before forging, so that less forming work is necessary during forging. Thus lower forces are necessary during forging in order in particular to displace material in particular toward the blade. The material is stressed less and there are more design possibilities regarding the design of bolster and blade shapes. Furthermore, costs are saved due to shorter production times and less waste.

To this end it is preferably proposed that the longitudinal axis of the bead forms an angle of 5° to 60° with the longitudinal axis of the knife. It is particularly advantageous if the longitudinal axis of the bead forms an angle of 15° to 35° with the longitudinal axis of the knife.

In one embodiment the two side edges of the bead extending transversely of the longitudinal axis of the knife extend parallel to each other. Alternatively, it is proposed that the two side edges of the bead extending transversely to the longitudinal axis of the knife are arranged to extend toward each other. The two side edges of the bead thus have a larger or smaller spacing from each other in the region of the knife back than at the opposite bead end.

Preferably, it is proposed that the first bead side edge turned toward the knife handle forms a larger acute angle with the knife longitudinal axis than the angle formed by the second bead side edge turned toward the knife blade. Preferably, the first bead side edge turned toward the knife handle forms an acute angle of 50° to 90° and the second bead side edge turned toward the knife blade forms an acute angle of 30° to 80° with the knife longitudinal axis.

It is also advantageous for production when, with upsetting of the bead, the region of the flat piece adjoining the oblique bead side edge (R1 or R2) is set obliquely with respect to the other flat piece region.

Embodiments of the invention are described in more detail below. Therein:

FIG. 1 show a flat piece of steel for making a knife;

FIG. 2 show the flat piece with the upset bead extending obliquely to the longitudinal extension;

FIG. 3 show the upset flat piece with forged knife sketched therein.

To produce a knife 1 with a blade 2, a bolster 3, and a tang 4 (to which handle plates are later attached), a flat piece 5 of steel is upset in the known manner to form a bead 6 in a central region. With the known method, the longitudinal axis LW of the bead 6 later forming the bolster 3 and the two side edges R1 and R2 of the bead 6 would extend at right angles to a longitudinal axis LF of the flat piece 5. During subsequent forging of the flat piece 5 to form the knife 1, the material of the bead 6 would be considerably stressed when a bolster 3 extending obliquely to the knife longitudinal axis LM is to be produced. With an oblique bolster of this type, at least the bolster side edge K1 turned toward the blade 2 extends obliquely to the knife longitudinal axis LM or to the knife longitudinal extension and the bolster tapers off with a region 3 a into the blade 2.

With the method according to the invention, the bead 6 extends obliquely to the longitudinal axis LF so that the longitudinal axis LW of the bead 6 and the bead side edges R1 and R2 form an angle α of less than 90° to the longitudinal axis LF of the flat piece. LW, R1 and R2 thus extend parallel to one another and the angle is 5° to 60°, preferably 15° to 35°.

Alternatively, in an embodiment that is not shown, the two side edges R1 and R2 of the bead 6 extending transversely to the longitudinal axis of the knife converge toward each other. The two side edges R1 and R2 of the bead 6 here have a larger or smaller distance from each other at the knife back than at the opposite bead end. The first bead side edge R1 turned toward the knife handle here forms a larger acute angle with the knife longitudinal axis LM than the angle of the second bead edge R2 turned toward the knife blade 2. The first bead side edge R1 turned toward the knife handle can also here form an acute angle of 50° to 90° and the second bead side edge R2 turned toward the knife blade 2 can form an acute angle of 30° to 80° with the knife longitudinal axis LM.

FIG. 3 shows how the bolster side edges extend relative to an oblique bolster 3. The first bolster side edge K1 turned toward the tang 4 extends essentially at right angles to the knife longitudinal axis LM and the second bolster side edge K2 extends obliquely to the knife longitudinal axis an angle α1 approximately equal to the angle α with the flat piece 5. The side edges K1 and K2 thus converge toward each other and in a similar manner the side edges R1 and R2 with the bead 6 can also be designed to converge toward each other, according to the unillustrated embodiment described above.

An oblique upsetting is achieved in during the upsetting operation in that the flat piece is pushed together in an uneven manner or the flat piece is still pushed together in a parallel manner and the oblique upsetting thereby results from the use of special electrodes. The electrodes are designed such that an exact “parallel” heating does not take place in the blank, instead, they heat the blank in different defined regions, so that the desired oblique upsetting occurs. 

1. A method of making a knife with a blade, a bolster, and a handle, from a single flat piece of steel, the method comprising the steps of: upsetting the flat piece is upset to form in the region between the blade and the handle a bead whose longitudinal axis extends obliquely to the knife longitudinal axis and thereafter forging the bead into a bolster that has at least one side edge (K2) extending obliquely to the knife longitudinal axis.
 2. The method according to claim 1, wherein the longitudinal axis of the bead forms an of 5° to 60° with the longitudinal axis of the knife.
 3. The method according to claim 1, wherein the longitudinal axis of the bead forms an angle of 15° to 35° with the longitudinal axis of the knife.
 4. The method according to claim 1, wherein the two side edges of the bead extending transversely to the longitudinal axis of the knife extend parallel to each other.
 5. The method according to claim 1, wherein the two side edges of the bead extending transversely to the longitudinal axis of the knife converge toward each other.
 6. The method according to claim 5, wherein the two side edges of the bead have a larger or smaller distance from each other in the region of the knife back than at the opposite bead end.
 7. The method according to claim 6, wherein the first bead side edge turned toward the knife handle forms a larger acute angle with the knife longitudinal axis than the angle of the second bead side edge turned toward the knife blade.
 8. The method according to claim 7, wherein the first bead side edge turned toward the knife handle forms an acute angle of 50° to 90° and the second bead side edge turned toward the knife blade forms an acute angle of 30° to 80° with the knife longitudinal axis.
 9. The method according to claim 5, wherein, with upsetting of the bead, the region of the flat piece adjoining the oblique bead side edge is displaced obliquely with respect to the other flat piece region of the bead. 